Hi! we are doing some measurements about the DPPH radical scavenging activity of seaweed extracts. We know that the main units used to express this activity are in %. But we have different sample weights for the same extractant volume (MetOH), and thus we need to normalize per sample weight. Somebody knows if is it correct to express the units as [% activity mg-1 DW] ?? any other suggestion?
thanks in advance
Hi, the best way to compare DPPH radical scavenging activity of different extracts is presenting the data as IC50, ppm. This is the concentration of extract needed to scavenge 50% of DPPH radical (%RSA).
You have to find a linear regression equation of the relationship between %RSA and extract concentration.
Good luck
Hi, the best way to compare DPPH radical scavenging activity of different extracts is presenting the data as IC50, ppm. This is the concentration of extract needed to scavenge 50% of DPPH radical (%RSA).
You have to find a linear regression equation of the relationship between %RSA and extract concentration.
Good luck
Please see this reference which will help you from the other direction (estimation of antioxidant activity by using DPPH free radical). Best Wishes.
Dear Jose Miguel Sandoval-Gil,
The results of the DPPH test are expressed as antiradical activity.
Antiradical activity I (%) = [(Ac - At) / Ac] x 100
Ac: Control Absorbance
At: Absorbance of the sample
The minimum 50% inhibitory concentration (IC50) is determined on the graph representing the percent inhibition of DPPH as a function of extract and standard concentrations. In order to better characterize the antiradical activity calculated for each concentration, 2 other parameters can be determined namely the 50% effector concentration (EC50) and the antiradical power (ARP) which is only the inverse of the EC50.
EC50 = IC50 / μg DPPH
Best regards
Dr Benkhaled A
- Badges
- Science topic
- Similar topics
- Phytochemistry
- Extracts